Liquid crystal display device

ABSTRACT

A liquid crystal display device includes a housing, a liquid crystal panel provided in the housing and comprises first and second transparent substrates spaced from each other at predetermined intervals, a sealing member to seal an internal space formed between the first and second transparent substrates, a liquid crystal to fill the internal space, first and second transparent electrodes formed in the first and second transparent substrates, respectively, and a polarizing plate to transmit light in a predetermined polarizing direction, a backlight unit disposed in the housing to emit surface light to the liquid crystal panel, and a polarizing filter disposed in the housing, and spaced from the liquid crystal panel at predetermined intervals to transmit predetermined polarized light and to block other polarized light of incident light.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. §119(a) from KoreanPatent Application No. 10-2007-0127207, filed on Dec. 7, 2007 and KoreanPatent Application No. 10-2008-0047241, filed on May 21, 2008 in theKorean Intellectual Property Office, the disclosure of which isincorporated herein in its entirety by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present general inventive concept relates to a liquid crystaldisplay device, and more particularly, to a liquid crystal displaydevice to be installed outdoors.

2. Description of the Related Art

Generally, a liquid crystal display (LCD) device is a type of a flatpanel display device, and includes a backlight unit emitting light and aliquid crystal panel selectively transmitting light from the backlightunit to form an image.

As liquid crystal panels have increased in size, demands and applicationareas for an LCD device having the large-sized liquid crystal panel havesharply increased.

If the LCD device is to be installed outdoors, the liquid crystal panelmay be exposed to sunlight having 1 kW/m² radiant energy. In this case,liquid crystals are heated by solar radiant energy, and may not bedriven normally. Thus, the successful outside installation of the LCDdevice is, in reality, unlikely without a sun blocking structure.

FIG. 1 is a perspective view illustrating an LCD device which isinstalled outdoors with a conventional light blocking plate.

As illustrated therein, the LCD device which can be installed outdoorsincludes a liquid crystal panel 1, and a light blocking plate 5 disposedin front of the liquid crystal panel 1 to prevent direct rays of lightfrom being incident to the liquid crystal panel 1.

To block sunlight emitted from above and lateral sides, the lightblocking plate 5 includes an upper plate 6 provided on the liquidcrystal panel 1 and protruding forward, and left and right plates 7 and8 provided at the left and right sides of the liquid crystal panel 1 andprotruding forward.

If the LCD device which can be installed outdoors includes the lightblocking plate 5 as described above, the direct rays of light isprevented from being incident to the liquid crystal panel 1.

However, the installed light blocking plate 5 narrows a viewing angle,and limits a viewing direction. Also, additional space is required toinstall the light blocking plate 5.

SUMMARY OF THE INVENTION

The present general inventive concept provides a LCD device to blocklight not contributing to displaying images among solar radiant energyincident to a liquid crystal panel, without an outwardly-protrudinglight blocking plate, and to protect the liquid crystal panel from thesolar radiant energy.

Additional aspects and utilities of the present general inventiveconcept will be set forth in part in the description which follows and,in part, will be obvious from the description, or may be learned bypractice of the general inventive concept.

The foregoing and/or other aspects and utilities of the present generalinventive concept can be achieved by providing a liquid crystal displaydevice comprising a housing, a liquid crystal panel provided in thehousing and comprises first and second transparent substrates spacedfrom each other at predetermined intervals, a sealing member to seal aninternal space formed between the first and second transparentsubstrates, a liquid crystal to fill the internal space, first andsecond transparent electrodes formed in the first and second transparentsubstrates, respectively, and a first polarizing plate to transmit lightin a predetermined polarizing direction, a backlight unit disposed inthe housing to emit surface light to the liquid crystal panel, and apolarizing filter disposed in the housing, and spaced from the liquidcrystal panel at predetermined intervals to transmit predeterminedpolarized light and to block other polarized light of incident light.

The first polarizing plate may be provided at an outside of the firsttransparent substrate to face the backlight unit.

The liquid crystal display device may further comprise a secondpolarizing plate provided at a lateral side of the second transparentsubstrate.

The polarizing filter and the second polarizing plate may be arranged sothat a polarizing direction of light transmitting the polarizing filteris substantially equal to that of light transmitting the secondpolarizing plate.

The liquid crystal display device may further comprise an infraredfilter provided at a lateral side of the polarizing filter to blocklight in the infrared area among incident light, and an ultravioletfilter provided at a lateral side of the infrared filter and to blocklight in the ultraviolet area among the incident light.

The liquid crystal display device may further comprise a heat radiatingmember provided in the housing to cool the liquid crystal panel and thepolarizing filter.

The heating radiating member may comprise at least one fan which isprovided in the housing to introduce external air to the housing or todischarge internal air of the housing to the outside.

The fan may be provided in a lower rear side of the housing to introducethe external air to a space between the liquid crystal panel and thepolarizing filter.

The fan may be provided in an upper rear side of the housing todischarge air from the housing to the outside.

The heat radiating member may comprise a heat absorber provided in thehousing to absorb heat, and a heat radiator provided outside of thehousing to discharge the heat absorbed by the heat absorber to theoutside.

A distance between the liquid crystal panel and the polarizing filter Dmay satisfy a following formula.

0.005≦D/L≦0.1

L=(H ² +W ²)^(1/2)

Here, H refers to a height of the liquid crystal panel, W is a width ofthe liquid crystal panel, D is the distance D between the liquid crystalpanel and the polarizing filter, and L is a diagonal length of theliquid crystal panel.

The foregoing and/or other aspects and utilities of the present generalinventive concept can be achieved by providing a liquid crystal displaydevice including a liquid crystal panel, one or more polarizing platesto transmit light in a predetermined polarized direction and block otherlight, and a polarizing filter spaced from the liquid crystal panel atone or more predetermined intervals, and to at least one of reflect andabsorb blocked light and to prevent the blocked light from beingdirectly applied to the liquid crystal display.

The foregoing and/or other aspects and utilities of the present generalinventive concept can be achieved by providing a liquid crystal displaydevice including a liquid crystal panel to display an image, a backlightunit to emit to emit surface light to the liquid crystal panel, apolarizing filter spaced from the liquid crystal panel at one or morepredetermined intervals, and to transmit polarized light and to blockother polarized light of incident light, a housing to enclose the liquidcrystal panel, the backlight unit and the polarizing filter, and a heatradiating member having a heat absorber to absorb heat from an internalspace inside the housing and a heat radiator to discharge the absorbedheat outside the housing.

The heat absorber may be disposed inside the housing and the heatradiator may be disposed outside the housing.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and/or other aspects and utilities of the present generalinventive concept will become apparent and more readily appreciated fromthe following description of the exemplary embodiments, taken inconjunction with the accompanying drawings, in which:

FIG. 1 is a perspective view illustrating a LCD device which isinstalled outdoors with a conventional light blocking plate;

FIG. 2 is a sectional view illustrating a LCD device according to anexemplary embodiment of the present general inventive concept;

FIG. 3 illustrates a detailed configuration of a liquid crystal panel inFIG. 2 and an external light blocking process of the LCD device in FIG.2;

FIG. 4 illustrates a size of the liquid crystal panel and a distancebetween the liquid crystal panel and a polarizing filter; and

FIG. 5 is a sectional view of a LCD device according to anotherexemplary embodiment of the present general inventive concept.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made in detail to embodiments of the presentgeneral inventive concept, examples of which are illustrated in theaccompanying drawings, wherein like reference numerals refer to likeelements throughout. The embodiments are described below so as toexplain the present general inventive concept by referring to thefigures.

FIG. 2 is a sectional view illustrating a LCD device according to anexemplary embodiment of the present general inventive concept. FIG. 3illustrates a detailed configuration of a liquid crystal panel in FIG. 2and an external light blocking process of the LCD device in FIG. 2.

As illustrated therein, the LCD device according to the exemplaryembodiment of the present general inventive concept includes a housing10, and a liquid crystal panel 20, a backlight unit 40 and a polarizingfilter 50 which are installed in the housing 10.

Referring to FIGS. 2 and 3, the liquid crystal panel 20 is a non-emittertype display panel. The liquid crystal panel 20 selectively transmitslight emitted by the backlight unit 40 to each of a plurality of pixelsforming an image. The liquid crystal panel 20 includes first and secondtransparent substrates 21 and 23, a sealing member 25, a liquid crystal26, first and second transparent electrodes 27 and 29 and a polarizingplate 30.

The first and second transparent substrates 21 and 23 are spaced fromeach other at predetermined intervals. The liquid crystal 26 is injectedbetween the first and second transparent substrates 21 and 23. Thesealing member 25 seals an internal space formed between the first andsecond transparent substrates 21 and 23.

The first and second transparent electrodes 27 and 29 are stripe-shapedelectrodes formed in the first and second transparent substrates 21 and23, respectively. The first transparent electrode 27 intersects analignment direction of the second transparent electrode 29. A switchingelement (not illustrated) is provided at an intersection of the firstand second transparent electrodes 27 and 29 and controls power suppliedto the first and second transparent electrodes 27 and 29 to turn on andoff each pixel of the liquid crystal 26.

The polarizing plate 30 may include a first polarizing plate 31 providedin an external part of the first transparent substrate 21 and a secondpolarizing plate 33 provided in an external part of the secondtransparent substrate 23.

The first polarizing plate 31 transmits light in a predeterminedpolarizing direction. That is, the first polarizing plate 31 transmitsspecific polarized light emitted by the backlight unit 40 to the liquidcrystal 26 and blocks other polarized light. The light which has passedthrough the first polarizing plate 31 progresses to the secondpolarizing plate 33, with a polarizing direction determined for eachpixel depending on a driving status of the pixel.

The second polarizing plate 33 transmits light in a predeterminedpolarizing direction and blocks other polarized light. Thus, the liquidcrystal panel 20 forms an image by blocking light which has passedthrough some pixels and by transmitting light which has passed throughother pixels, corresponding to the driving status of the liquid crystal26.

In this embodiment, the polarizing plate 30 includes the firstpolarizing plate 33 and the second polarizing plate 33, but not limitedthereto. Alternatively, the polarizing filter 50 may perform an opticalfunction of the second polarizing plate 33 as described below. Thus, inanother embodiment, the second polarizing plate 33 may be removed.

The backlight unit 40 is installed in the housing 10, faces the firstpolarizing plate 31 and emits surface light to the liquid crystal panel20.

According to the present embodiment, the backlight unit 40 is an edgeemitting type, and includes a light source 41 and a light guiding plate45 to guide a progress direction of the light emitted by the lightsource 41. The light source 41 includes a lamp 43 and a reflectionmirror 44 to reflect light emitted by the lamp 43 to the light guidingplate 45. The light source 41 may include, for example, at least onelight emitting diode (LED) disposed at an edge of the light guidingplate 45. The backlight unit 40 is not limited to the edge emittingtype, and may include a direct emitting type.

The polarizing filter 50 is spaced from the liquid crystal panel 20 atpredetermined intervals, and transmits predetermined polarized light ofincident light and blocks other polarized light. Thus, if the LCD deviceis installed outdoors, a portion of sunlight incident from the outsideis blocked. For example, in the present general inventive concept,approximately 50%, for example, may be blocked. Thus, the liquid crystalpanel 20 is prevented from being thermal damaged by sunlight. As thepolarizing filter 50 is spaced from the liquid crystal panel 20, lightwhich is absorbed or reflected by the polarizing filter 50 to blocksunlight is not directly applied to the liquid crystal panel 20.

To transmit an image formed by the liquid crystal panel 20, thepolarizing filter 50 is disposed in consideration of the alignmentdirection of the second polarizing plate 33. That is, the polarizingfilter 50 and the second polarizing plate 33 are arranged so that thepolarizing direction of the light transmitting the polarizing filter 50is substantially equal to that of light transmitting the secondpolarizing plate 33. As most of the image formed on the liquid crystalpanel 20 transmits through the polarizing film 50, a lowering ofbrightness due to the polarizing filter 50 does not occur.

Here, the polarizing filter 50 transmits light polarized in apredetermined direction therethrough and blocks other polarized light,thereby serving as the second polarizing plate 33. Accordingly, theimage can be formed without the second polarizing plate 33.

The LCD device according to the exemplary embodiment of the presentgeneral inventive concept may further include an infrared filter 61 andan ultraviolet filter 65 which are provided in the housing 10.

The infrared filter 61 is provided in a lateral side of the polarizingfilter 50 and blocks light in the infrared area among incident light.The ultraviolet filter 65 is provided in a lateral side of the infraredfilter 61 and blocks light in the ultraviolet area among the incidentlight.

If the LCD device further includes the infrared filter 61 and theultraviolet filter 65, infrared rays (IR) and ultraviolet rays (UV)included in the solar radiant energy, i.e., approximately 50% of thesolar radiant energy, is blocked.

Thus, about 50% of the incident solar radiant energy is blocked by theinfrared filter 61 and the ultraviolet filter 65, and another 50% of theremaining solar radiant energy transmitting the infrared and ultravioletfilters 61 and 65 is blocked by the polarizing filter 50. As a result,only about 25% of the overall radiant energy passes through the filters61, 65 and 50 and is incident to the liquid crystal panel 20, sharplyreducing an impact of the solar radiant energy.

Even if the light blocking plate is not used, the liquid crystal 26 ofthe LCD device does not rise to a critical temperature.

The LCD device according to another embodiment may further include aheat radiating member 70 to cool the liquid crystal panel 20 and thepolarizing filter 50.

The heat radiating member 70 may include at least one fan which isprovided in the housing 10.

FIG. 2 illustrates first and second fans 71 and 73 as an example of theheat radiant member 70. Referring to FIG. 2, the first fan 71 isprovided in a lower rear side of the housing 10 to introduce externalair to a space 75 between the liquid crystal panel 20 and the polarizingfilter 50. The second fan 73 is provided in an upper rear side of thehousing 10 to discharge air from the housing 10 to the outside.

As described above, if the LCD device includes the first and second fans71 and 73 as the heat radiating member 70, air circulates in and aroundthe housing 10, and the liquid crystal panel 10 and the polarizingfilter 50 may be more efficiently cooled. Since impurities may beintroduced to the housing 10 when air circulates in and around thehousing 10, an air filter (not illustrated) may be provided in anopening of the housing 10 having the first and second fans 71 and 73 toprevent the impurities.

FIG. 4 illustrates a size of the liquid crystal panel 20 and a distancebetween the liquid crystal panel 20 and the polarizing filter 50.

Referring to FIG. 4, a distance D between the liquid crystal panel 20and the polarizing filter 50 can be determined, for example, inconsideration of a size of the liquid crystal panel 20. That is, ifother conditions are equal, a larger liquid crystal panel receives moresolar radiant energy. Then, the liquid crystal is very likely to bedamaged. Considering such circumstances, the distance D can satisfy afollowing formula 1.

0.005≦D/L≦0.1

L=(H ² +W ²)^(1/2)   [Formula 1]

Here, H refers to a height of the liquid crystal panel 20, W is a widthof the liquid crystal panel 20, D is the distance D between the liquidcrystal panel 20 and the polarizing filter 50, and L is a diagonallength of the liquid crystal panel 20.

In the formula 1, a lowest value is a value where boundary layers of airflow in the liquid crystal panel 20 and the polarizing filter 50 meeteach other when the liquid crystal panel 20 and the polarizing filter 50are cooled by the first and second fans 71 and 73. If D/L is out of thelowest value, air flow between the liquid crystal panel 20 and thepolarizing filter 50 is fully developed. Thus, a convective heattransfer coefficient is drastically reduced.

In the formula 1, a highest value of D/L does not exist in the thermalaspect. If D/L is out of the highest value of the formula 1, a thicknessof front and rear surfaces of the LCD device is very thick compared to ascreen size, creating limitations in an installing space.

FIG. 5 is a sectional view illustrating a LCD device according toanother exemplary embodiment of the present general inventive concept.

As illustrated therein, the LCD device according to the presentembodiment includes a housing 110, and a liquid crystal panel 20, abacklight unit 40 and a polarizing filter 50 which are provided in thehousing 110. The LCD device may further include an infrared filter 61,an ultraviolet filter 65 and a heat radiating member 170. The LCD deviceaccording to the present embodiment is differentiated from thataccording to the exemplary embodiment, illustrated in FIG. 2, in thatthe housing 110 is a closed configuration and a configuration of theheat radiating member 170 is changed.

As the housing 110 is a closed configuration, air does not circulate inand around the housing 110 unlike in the exemplary embodiment. Thus,external impurities are not introduced to the housing 110 fundamentally.

The heat radiating member 170 is provided in and outside of the housing110. The heat radiating member 170 includes a heart absorber 171 whichis provide in the housing 110 to absorb heat from an internal space ofthe housing 110, and a heat radiator 173 which is provided out of thehousing 110 to discharge heat absorbed by the heat absorber 171 to theoutside. The heat absorbed by the heat absorber 171 is applied to theheat radiator 173, and the heat radiator 173 discharges the heat to theoutside of the housing 110. Thus, the inside of the housing 110 may becooled.

FIG. 5 illustrates a heat sink having a plurality of heat radiating finsas an example of the heat radiating member 170, but not limited thereto.Alternatively, the heat radiating member 170 may include a heat pipe. Asa configuration and an operation of the heat pipe is known, detaileddescription will be avoided.

As described above, the LCD device according to various embodiments ofthe present general inventive concept includes an additional polarizingfilter spaced from a liquid crystal panel within a housing to blockother light than predetermined polarized light of incident light. Thus,even if the LCD device is installed outside, direct emission of solarradiant energy to the liquid crystal panel may be eased. Even ifinstalled outside, the liquid crystal panel of the LCD device may beprevented from being overheated.

The LCD device according to various embodiments of the present generalinventive concept further includes an infrared filter and an ultravioletfilter as well as the polarizing filter to block light in the infraredarea and the ultraviolet area included in solar radiant energy toprotect the liquid crystal panel from the solar radiant energy moreefficiently.

The LCD device according to various embodiments of the present generalinventive concept further includes a heat radiating member to cool theliquid crystal panel and a polarizing filter in a housing. As internaltemperature of the housing is lowered, internal temperature of thehousing may be prevented from rising.

Since the LCD device according to various embodiments of the presentgeneral inventive concept does not use a liquid blocking plateprotruding outwardly, a wide viewing angle may be secured and limitationof an installing space may be reduced.

Although various exemplary embodiments of the present general inventiveconcept have been illustrated and described, it will be appreciated bythose skilled in the art that changes may be made in these embodimentswithout departing from the principles and spirit of the generalinventive concept, the scope of which is defined in the appended claimsand their equivalents.

1. A liquid crystal display device, comprising: a housing; a liquidcrystal panel provided in the housing and comprises first and secondtransparent substrates spaced from each other at predeterminedintervals, a sealing member to seal an internal space formed between thefirst and second transparent substrates, a liquid crystal to fill theinternal space, first and second transparent electrodes formed in thefirst and second transparent substrates, respectively, and a firstpolarizing plate to transmit light in a predetermined polarizingdirection; a backlight unit disposed in the housing to emit surfacelight to the liquid crystal panel; and a polarizing filter disposed inthe housing, and spaced from the liquid crystal panel at predeterminedintervals to transmit predetermined polarized light and to block otherpolarized light of incident light.
 2. The liquid crystal display deviceaccording to claim 1, wherein the first polarizing plate provided at anoutside of the first transparent substrate to face the backlight unit.3. The liquid crystal display device according to claim 2, furthercomprising: a second polarizing plate provided at a lateral side of thesecond transparent substrate.
 4. The liquid crystal display deviceaccording to claim 3, wherein the polarizing filter and the secondpolarizing plate are arranged so that a polarizing direction of lighttransmitting the polarizing filter is substantially equal to that oflight transmitting the second polarizing plate.
 5. The liquid crystaldisplay device according to claim 1, further comprising: an infraredfilter provided at a lateral side of the polarizing filter to blocklight in the infrared area among incident light; and an ultravioletfilter provided at a lateral side of the infrared filter to block lightin the ultraviolet area among the incident light.
 6. The liquid crystaldisplay device according to claim 5, further comprising: a heatradiating member provided in the housing to cool the liquid crystalpanel and the polarizing filter.
 7. The liquid crystal display deviceaccording to claim 6, wherein the heating radiating member comprises: atleast one fan provided in the housing to introduce external air to thehousing or to discharge internal air of the housing to the outside. 8.The liquid crystal display device according to claim 7, wherein the fanis provided in a lower rear side of the housing to introduce theexternal air to a space between the liquid crystal panel and thepolarizing filter.
 9. The liquid crystal display device according toclaim 7, wherein the fan is provided in an upper rear side of thehousing to discharge air from the housing to the outside.
 10. The liquidcrystal display device according to claim 6, wherein the heat radiatingmember comprises: a heat absorber provided in the housing to absorbheat; and a heat radiator provided outside of the housing to dischargethe heat absorbed by the heat absorber to the outside.
 11. The liquidcrystal display device according to claim 1, wherein a distance betweenthe liquid crystal panel and the polarizing filter satisfies a followingformula.0.005≦D/L≦0.1L=(H ² +W ²)^(1/2) Here, H refers to a height of the liquid crystalpanel, W is a width of the liquid crystal panel, D is the distance Dbetween the liquid crystal panel and the polarizing filter, and L is adiagonal length of the liquid crystal panel.
 12. A liquid crystaldisplay device, comprising: a liquid crystal panel; one or morepolarizing plates to transmit light in a predetermined polarizeddirection and block other light; and a polarizing filter spaced from theliquid crystal panel at one or more predetermined intervals, and to atleast one of reflect and absorb blocked light and to prevent the blockedlight from being directly applied to the liquid crystal display.
 13. Aliquid crystal display device, comprising: a liquid crystal panel todisplay an image; a backlight unit to emit to emit surface light to theliquid crystal panel; a polarizing filter spaced from the liquid crystalpanel at one or more predetermined intervals, and to transmit polarizedlight and to block other polarized light of incident light; a housing toenclose the liquid crystal panel, the backlight unit and the polarizingfilter; and a heat radiating member having a heat absorber to absorbheat from an internal space inside the housing and a heat radiator todischarge the absorbed heat outside the housing.
 14. The liquid crystaldisplay device according to claim 13, wherein the heat absorber isdisposed inside the housing and the heat radiator is disposed outsidethe housing.